[[modules-cluster]] == Cluster One of the main roles of the master is to decide which shards to allocate to which nodes, and when to move shards between nodes in order to rebalance the cluster. There are a number of settings available to control the shard allocation process: * <> lists the settings to control the allocation an rebalancing operations. * <> explains how Elasticsearch takes available disk space into account, and the related settings. * <> and <> control how shards can be distributed across different racks or availability zones. * <> allows certain nodes or groups of nodes excluded from allocation so that they can be decommissioned. Besides these, there are a few other <>. All of the settings in this section are _dynamic_ settings which can be updated on a live cluster with the <> API. include::cluster/shards_allocation.asciidoc[] include::cluster/disk_allocator.asciidoc[] include::cluster/allocation_awareness.asciidoc[] include::cluster/allocation_filtering.asciidoc[] include::cluster/misc.asciidoc[]